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GCN Circulars

GCN Circulars are rapid bulletins submitted by and distributed to the community. See the documentation for help with subscribing to or submitting Circulars.

Search for Circulars by submitter, subject, or body text (e.g. 'Fermi GRB').
To navigate to a specific circular, enter the associated Circular ID (e.g. 'gcn123', 'Circular 123', or '123').
Advanced Search

To narrow the search results, use advanced search syntax. This allows for specifying which circular field to search (submitter, subject, and/or body). For additional information, refer to the advanced search documentation.

Advanced Search Examples (click to copy):

subject:"Swift"
body:"GRB"
submitter:"Judith Racusin"

32763 results found.

  1. LIGO/Virgo/KAGRA S250727dc: Swift-XRT observations, 8 X-ray sources
  2. GRB 250725A: AstroSat CZTI detection
  3. GRB 250727A: EP-FXT follow-up observation
  4. GRB 250725A: PRIME near-infrared observations
  5. LIGO/Virgo/KAGRA S250727dc: DECam GW-MMADS upper limits of AT 2025smm
  6. LIGO/Virgo/KAGRA S250727dc: PRIME J-band upper limits of AT 2025smm
  7. GRB: Clarification on Gamma-Ray Burst Naming Convention
  8. GRB 250727A: SVOM/ECLAIRs refined analysis
  9. EP-WXT trigger 01709195487: confirmation of a stellar flare by BOOTES-6 & BOOTES-7
  10. GRB 250728A: COLIBRÍ optical upper limit
  11. GRB 250728A: Fermi GBM Observation
  12. LIGO/Virgo/KAGRA S250727dc: Updated Sky localization
  13. GRB 250728A: Swift ToO observations
  14. GRB 250728A: Swift/BAT-GUANO arcminute localization of a short burst
  15. GRB 250727A: AST3-2 Upper limit
  16. LIGO/Virgo/KAGRA S250727cl: Updated Sky localization
  17. GRB 250727A: EP-FXT counterpart detection
  18. GRB250727A: SVOM/VT optical upper limit
  19. LIGO/Virgo/KAGRA S250727dc: Identification of a GW compact binary merger candidate
  20. LIGO/Virgo/KAGRA S250727cl: Identification of a GW compact binary merger candidate
  21. LIGO/Virgo/KAGRA S250725j: DECam GW-MMADS candidates
  22. LIGO/Virgo/KAGRA S250725l: Updated Sky localization
  23. LIGO/Virgo/KAGRA S250726ak: Updated Sky localization
  24. LIGO/Virgo/KAGRA S250726ak: Identification of a GW compact binary merger candidate
  25. GRB 250725A: Fermi GBM Observation
  26. LIGO/Virgo/KAGRA S250725j: Updated Sky localization
  27. GRB 250725A: Swift-BAT refined analysis
  28. Konus-Wind detection of GRB 250725A
  29. GRB 250725A: SVOM/GRM observation
  30. GRB 250725A: Global MASTER-Net: First Optical Synchronous Observatios of Short GRB.
  31. GRB 250725A: Swift/UVOT Upper Limits
  32. GRB 250725A: Fermi-LAT detection
  33. GRB 250725A: VLT/FORS2 spectroscopic redshift z = 5.26
  34. GRB 250725A: BOOTES-7 early optical detection
  35. GRB 250725A: SVOM/VT optical candidate
  36. LIGO/Virgo/KAGRA S250725l: Identification of a GW compact binary merger candidate (duplicate submission)
  37. LIGO/Virgo/KAGRA S250725l: Identification of a GW compact binary merger candidate
  38. LIGO/Virgo/KAGRA S250725j: Identification of a GW compact binary merger candidate
  39. EP250702a/GRB250702 B,E,D: MeerKAT radio observations at 3.06 GHz
  40. SVOM J195836+32283 is not a real source
  41. SVOM J195836+32283/sb25072103: Second VT observation
  42. SVOM J195836+32283/sb25072103: Liverpool Telescope detection of an extended source
  43. GRB 250721A: Fermi GBM Observation
  44. SVOM J195836+32283/sb25072103: Swift XRT/UVOT upper limits
  45. SVOM J195836+32283/sb25072103: NIR observations with WINTER
  46. GRB 250713A : SVOM/ECLAIRs refined analysis
  47. GRB 250717B: SVOM/GRM observation
  48. LIGO/Virgo/KAGRA S250711q: Updated Sky localization
  49. GRB 250721A: Tiled Swift observations
  50. GRB 250721A: MAXI/GSC detection
  51. LIGO/Virgo/KAGRA S250720j: Retraction of GW compact binary merger candidate
  52. EP250702a/GRB250702B,D,E: SVOM/VT optical upper limit
  53. GRB 250717B: COLIBRÍ optical upper limit
  54. GRB 250718B: Fermi GBM Final Localization Correction
  55. Swift Trigger 1334535 / GRB 250718A: COLIBRÍ optical upper limits
  56. GRB 250717B: Swift ToO observations
  57. GRB 270713A: Kitab and AbAO Optical Observations
  58. GRB 250717B: Fermi GBM Observation
  59. GRB 250717B: Swift/BAT-GUANO arcminute localization of a burst
  60. Konus-Wind detection of GRB 250716A
  61. GRB 250716A: Lesedi Detection of Fading Optical Transient GOTO25eyp
  62. GRB 250716A: Swift ToO observations
  63. GRB 250714A: SVOM/GRM observation
  64. Fermi GRB 250716A: Global MASTER-Net observations report
  65. Fermi GRB 250715A: Global MASTER-Net observations report
  66. EP250702a / GRB 250702B,D,E: Hubble Space Telescope Observations
  67. GRB 250702B,D,E / EP250702a: H.E.S.S. very-high-energy gamma-ray observations
  68. GRB 250713A: Mephisto optical upper limits
  69. Fermi GRB 250714A: Global MASTER-Net observations report
  70. GRB 250713A: SVOM/VT optical upper limit
  71. GRB 250713A: NOT optical upper limits
  72. GRB 250713A: OHP/T193 upper limit
  73. GRB 250713A: SVOM/C-GFT upper limit
  74. GRB 250706B/C: 7DT Follow-up Observations
  75. GRB 250713A: EP-FXT counterpart detection
  76. EP250711a: COLIBRÍ continuous optical observations
  77. GRB 250706A: Swift-BAT refined analysis
  78. GRB 250702F: Swift-BAT refined analysis
  79. GRB 250628A: Swift-BAT refined analysis
  80. LIGO/Virgo/KAGRA S250712cd: Updated Sky localization
  81. GRB 250713A: JinShan optical upper limits
  82. EP250711a: Global MASTER-Net observations report
  83. GRB 250711A: DDOTI Optical Upper Limit
  84. LIGO/Virgo/KAGRA S250712cd: Identification of a GW compact binary merger candidate
  85. EP250711a: COLIBRÍ refined photometry and optical confirmation of the candidate (duplicate submission)
  86. EP250711a: COLIBRÍ refined photometry and optical confirmation of the candidate
  87. GRB 250711A: SVOM/GRM observation
  88. EP250711a: NOT optical counterpart candidate
  89. EP250711a: EP-WXT detection and FXT follow-up observation of a fast X-ray transient
  90. Fermi GRB 250711A: Global MASTER-Net observations report
  91. EP250702a: gamma-ray upper limits from joint observations by the LST-1 and MAGIC telescopes
  92. GRB 250704A: GRANDMA observations
  93. GRB 250704A: SVOM/ECLAIRs refined analysis
  94. LIGO/Virgo/KAGRA S250711q: Identification of a GW compact binary merger candidate
  95. GRB 250702B,D,E/EP250702A: JCMT sub-mm observations at 350 GHz
  96. GRB 250704B / EP250704a: 1.3 GHz MeerKAT Detection
  97. GRB 250702B,D,E / EP250702a: ALMA detection
  98. IceCube-250708A: No Candidates from WINTER
  99. IceCube-250708A: No Candidate Transients from the Zwicky Transient Facility
  100. GRB 250702B,D,E / EP250702a: 10 GHz detection with the VLA

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